Hydropneumatic accumulator



Dec. 16, 1969 D. c. w. MORLEY HYDROPNEUMATIC ACCUMULATOR 4 Sheets-Sheet 1 Filed March 13, 1967 INVENTOR:

DAVID CHRISTOPHER WALTON MORLE-Y BY g/rwfl, S my Dec. 16, 1969 D. c. w. MORLEY 3,483,893

HYDROPNEUMATIC ACCUMULATOR Filed March 13, 1967 4 Sheets-Sheet 2 INVENTOR:

DAV! D CHRBTOPHER WALTON NOR LE'Y Dec. w, M69 D, c. WIM'ORLEY 3,483,893

HYDROPNEUMATIC ACCUMULATOR Filed March 13, 1967 4 Sheets$heet 3 FlG.3.

ZNVENTOR:

DAVI D CH RJ$TOPHER WALTON FmRLE-y Dec. 16, 1969 D, c. w. MORLEY 3,483,893

HYDROPNEUMATIC ACCUMULAI'OR Filed March 15, 1967 4 Sheets-Sheet A FIG-5A FIG-7A I FIG.6

FIGJ.

F1690 m 312 L J FIG.9B

FIG.9A

FIG 8 iNVENTOR;

DAVKD CHRISTOPHER WALTON MORLEY 3,483,893 HYDROPNEUMATIC ACCUMULATOR David C. W. Morley, Castle Donington, England, assignor to Hydrotrole Limited, Heaton Chapel, Stockport, Cheshire, England Filed Mar. 13, 1967, Ser. No. 622,774 Claims priority, application Great Britain, Mar. 11, 1966, 10,703/66; May 7, 1966, 20,331/66 Int. Cl. F161 55/02, 55/04 US. Cl. 138-30 2 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a hydropneumatic accumulator in which the bladder is arranged to receive a relatively incompressible hydraulic fluid and the portion of the accumulator outside the bladder is arranged to receive the compressible fluid, the bladder being substantially elongated and parallel sided.

The invention concerns hydropneumatic accumulators and has more particular reference to gas loaded accumulators of the bladder type.

The primary object of the present invention is to provide an improved form of accumulator of the type referred to which is of simple construction and which is reliable in operation.

The present invention is predicated upon the appreciation that in conventional accumulators, generally the bladder is either totally unsupported or is supported only under minimum load conditions. Ideally, the bladder will be supported when under maximum load conditions thus to reduce the risk of rupture but by virtue .of the very nature of known structures this is not possible.

However, it has been appreciated that if the hydraulic fluid is fed to or taken from the bladder and a readily compressible fluid is disposed about the bladder, then under maximum load conditions for the bladder the latter can be caused to seat against the body of the accumulator and thus be supported thereby. As a consequence, the risk of rupture will be much reduced in that the load is taken by the body and not by the bladder.

Thus, according to one aspect of the present invention, in using an hydropneumatic accumulator, I propose to apply the hydraulic fluid to the interior of the bladder and the readily compressible fluid media to the exterior of the bladder.

According to another aspect of the present invention, there is provided an hydropneumatic accumulator comprising a body part, the volume of which is divided into two portions by a bladder located within the body part, that portion of the volume of the body part exterior of the bladder being adapted to contain a compressible fluid medium and a port arranged to allow passage of a relatively incompressible fluid into and out of the bladder.

The invention also includes an hydropneumatic accumulator comprising a body part having a closed end thereto, an open-ended bladder disposed within the said body part and having the said open-end directed outwardly of the said body part, a closure means extending across the said open-end of the bladder, and feed means adapted to apply a compressible fluid medium to the exterior of said bladder and a relatively incompressible fluid medium to the interior of said bladder.

Preferably the bladder is substantially elongated and parallel sided.

The bladder may have many different shapes e.g. it may be of cruciform cross-section.

Preferably however, for economy of molding, the bladder is elongated, is open at one end and has one of the following cross-sections:

nited States Patent C) (i) Substantially square at the open end and tending toward cruciform at the closed end.

(ii) Substantially oval at the open end and tending to trifurcated at the closed end.

(iii) Substantially oval at the open end and tending towards cigar-shaped at the closed end.

The internal surface of the bladder is preferably provided with at least one closure member e.g. a button disc or the like arranged to co-operate with the port or ports for passage of the relatively incompressible fluid, when the bladder is under minimum load conditions, whereby the bladder is precluded from entering the port or ports.

The invention will now be described by way of example with reference to the accompanying drawings.

FIG. 1 is a sectional elevation of one form of hydropenumatic accumulator according to the invention and is a section along X-X of FIG. 2.

FIG. 2 is a sectional plan view of the accumulator of FIG. 1.

FIG. 3 is a sectional elevation of the bladder.

FIG. 4 is an elevational view of a modified form of bladder which may be used in an hydropneumatic accumulator of the invention.

FIG. 5 includes cross-sections of the bladder of FIG. 4 along lines AA BB and CC of FIG. 4.

FIG. 6 illustrates another modified form of bladder which may be used in an hydropneumatic accumulator of the invention.

FIG. 7 includes cross-sections of the bladder of FIG. 6 along lines AA, BB and CC of FIG. 6.

FIG. 8 illustrates a further modified form of bladder which may be used in an hydropneumatic accumulator of the invention and FIG. 9 includes cross-sections of the bladder of FIG. 8 along lines AA, BB and CC of FIG. 8.

Referring now to FIGS. 1 to 3 of the drawings, a hydropneumatic accumulator comprises a generally cylindrical body part 11 and an open-ended bladder 12 disposed within the body of part 11 and extending in the axial direction thereof, the bladder 12 being generally parallel sided as shown in FIG. 3. A base plate 13 is attached to the body part 11 adjacent to the open end of the bladder 12. The bladder is secured from the base plate 13 and is secured relative to the body part by any convenient means. The sided bladder 12 has a small conical top and a radially outwardly extending lip 12:: about the periphery of the open end, such lip serving to facilitate the attachment in position of the bladder within the body part. When viewed in trans verse crosssection the bladder is of cruciform or star shape (FIG. 2), the ribs 12b so formed serving to impart an additional degree of rigidity to the structure and militating against the complete collapse thereof when the internal pressure is reduced. Four opposed discs 16 are secured to the inner surface of the bladder in positions and for a purpose to be made apparent.

The base plate 13 has a stepped periphery thereto to facilitate the location thereof in the end of the body part and that surface 13a thereof directed towards the interior of the body part and thus of the bladder is upwardly conical. Four passages 13b are provided in the base plate, such passages extending between a source of hydraulic fluid as indicated by a feed conduit 13c and the conical surface 13a of the base plate.

The ends of the :passages 13b are so positioned in the surface of the base plate 13 as to receive the discs 16 into contact therewith upon the collapse of the bladder, such an arrangement of parts precluding the entry of the material of the bladder into the passage upon collapse of the bladder.

The clamping ring 14 is located against a shoulder 11a defined by an increased internal diameter portion of the body part and has an inclined outer surface 14a to receive the bladder in the erect condition thereof.

The end plate 15 engages the upper end of the body part and is secured relative thereto by appropriate welding as shown. An axial port 19 for passage of a compressible fluid medium is provided in the end plate 15. The end plate 15 seats on a cushion ring 18 of elastic material which is held in position by means of a circlip 17. The circlip 17 facilitates positioning of the end plate 15.

In use, hydraulic fluid is applied to the interior of the bladder, while pressure gas is fed to the space 17 between the bladder and body part, such an arrangement being the converse of that of conventional accumulators where the air or other readily compressible fluid medium is fed to the bladder, the latter usually being a closed bag, and the hydraulic fluid to the space.

It will be apparent that many modifications of the accumulator shown in FIGS. 1 to 3 may be made within the scope of the invention. For example, the body part may be formed in many different ways. It may, for example, be formed integrally with the end plate 15 by pressing from sheet metal. Also many different forms of bladder may be used. A number of these alternative shapes of bladder are shown in FIGS. 4 to 9. FIGS. 4 and 5 show a bladder 112 of elongated open ended construction having a substantially square cross-section at its open end and a cross-section which tends to cruciform towards its closed end. FIGS. 6 and 7 show a bladder 212 of elongated open ended construction having a substantially triangular cross-section at its open end and a cross-section which tends to trifurcated towards its closedend. FIGS. 8 and 9 show a bladder 312 which again is elongated and open-ended but which has a roughly oval cross-section at its open end and flattens to a cross-section which is roughly cigar-shaped towards its closed end.

The arrangement described in connection with the drawings has the advantage that the bladder 12, being filled with the relatively incompressible fluid medium, is supported by the walls of the body part 11 in an uncreased condition when under maximum pressure and is only subjected to a folded condition when the gas has expanded, and is therefore at minimum pressure. This is the reverse of known bladder type accumulators. Furthermore the bladder 12 may be molded in its folded condition so that this folded condition possesses some degree of stability. As the bladder 12 is secured at the end of the device through which the relatively incompressible fluid medium enters and leaves the bladder, the ports 13b may generally be reliably closed by inserts 16. This function is not generally altered by the length of the container and this type of port closure may therefore be used in large and small models alike. In known bladder type accumulators the port for the relatively incompressible fluid medium is closed by buttons or studs mounted on the unclamped end of the bladder thus resulting in considerable unreliability in positioning of the stud or button over the port.

A further advantage of this arrangement is that since the bladder 12 is filled with the hydraulic fluid the walls of the body part 11 of the accumulator do not have to be compatible with the hydraulic fluid.

As the inserts 16 are not in the region of the ports 13a at the beginning of the bladder exhaust, the ports 13a are not subject to premature closure due to a sudden pressure drop or differential and higher instantaneous flow rates may therefore be used.

The open end of the bladder 12 neck is not in the proximity of the port 19 and this port may thus be connected to other gas vessels which may supply and remove volumes of gas at a high rate with less chance of injuring the bladder than in known bladder type accumulators. Consequently in many instances a saving may be made in the size of an accumulator used to give a relatively low pressure differential.

The bladder 12 may be made in one operation, normally molded in a horizontal position, and normally the weakest point of a bladder, i.e. its seam or sea-ms may thus be eliminated thus enabling the bladder to operate over a wider range of temperature and diversity of fluids for a given bladder material than would otherwise be possible.

Further advantage may be gained from the bladder 12 moving towards and away from the side walls of the body part 11 in operation whereas generally in known accumulators the expansion and contraction of the bladder is mainly in an axial direction.

The accumulator of the present invention may be used in any one of a wide variety of ways for example, it may be used as a source of hydraulic power storage, as a transfer barrier between two fluids, as a method of absorbing fluid shock and/or pulsation, and as a compensator for temperature expansion or leakage.

I claim:

1. A hydropneumatic accumulator comprising in combination,

a body part having opposite closed ends,

one of the ends of the body part being closed by a ported end plate attachable to the body part and the opposite end being closed by a base plate attachable to the body part, an elongated collapsible bladder disposed within the body part and having a lipped open end adjacent the end of the body part closed by the base plate and having a substantially square cross section at its open end and a cruciform cross section at its closed end.

clamping means for securing the lipped open end of the bladder between the body part and base plate,

the base plate being provided with passage means therethrough for feeding an incompressible hydraulic fluid to the bladder interior,

means for closing off the passage means of the base plate upon bladder deflation,

the port of the end plate serving as means for feeding a compressible pressure gas to the space between the bladder and body part,

the bladder and body part and the space therebetween being arranged for the introduction of hydraulic fluid to the bladder interior during the introduction of pressure gas to the space between the bladder and body part with any reduction of the pressure within the bladder relative to the pressure in the space outside of the bladder but within the body part causing the bladder to deflate inwardly and with the bladder having substantially no internal volume in its maximum possible deflated condition,

the bladder being filled with the relatively incompressible fluid medium and supported by the walls of the body part in an uncreased condition when under maximum pressure and only subjected to a folded condition when the gas has expanded and is therefore at minimum pressure.

2. A hydropneumatic accumulator comprising in combination,

a body part having opposite closed ends,

one of the ends of the body part being closed by a ported end plate attachable to the body part and the opposite end being closed by a base plate attachable to the body part,

an elongated collapsible bladder disposed within the body part and having a lipped open-end adjacent the end of the body part closed by the base plate and having a substantially square cross section at its open end and a cruciform cross section at its closed end, clamping means for securing the lipped open end of the bladder between the body part and base plate, the base plate being provided with passage means therethrough for feeding an incompressible hydraulic fluid to the bladder interior,

the bladder having adjacent its open end an outwardly 5 6 extending flared portion overlying the passage means condition when the gas has expanded and is thereand adapted to move over the passage means when fore at a minimum pressure. the pressure in said bladder falls below a predeteri d amount, References Cited the port of the end plate serving as means for feeding 5 UNITED STATES PATENTS a compressible pressure gas to the space between the 3,424,201 1/1969 Sugimura et a1. thbladder and body Part 2,246,667 6/1941 Colman 138-30 XR e bladder and body part and the space therebetween 2 904 077 9/1959 Tmm er being arranged for the introduction of hydraulic fluid 2337771 12/1943 g 138 30 to the bladder interior during the introduction of 10 2532143 11/1950 B reit pressure gas to the space between the bladder and 2:760:518 8/1956 Peat 138 30 body part With any reduction of the pressure Within 2,736,438 3/1957 Mercier 138 30 the bladder relative to the pressure in the space out- 2,851,059 9/1953 Lucien Side of the bladder but Within the body part causing 3 277 925 10 19 Sugimura g 0 the bladder to deflate inwardly and with the bladder 10 3,34 573 10 19 7 Mercia 13g 3 having substantially no internal volume in its maximum possible deflated condition, FOREIGN PATENTS the bladder being filled with the relatively incompres- 124 33 5 1947 Australia sible fluid medium and supported by the Walls of the 90 241,065 10/1962 Australia. body part in an uncreased condition when under d maximum pressure and only subjected to a folded ROBERT MACKEY, Primary Examine! 

